A cell has an electric-generating element for performing charge and discharge and a battery case for housing the electric-generating element. The battery case accommodates an electrolytic solution in addition to the electric-generating element. For manufacturing the cell, the electric-generating element is put into the battery case and then the electrolytic solution is injected into the battery case by using an injection port formed in the battery case. The injection port is closed by a cap after the injection of the electrolytic solution.
The battery case has a valve for discharging gas produced within the battery case to the outside thereof. When the internal pressure of the battery case reaches the operation pressure of the valve due to the production of the gas, the valve changes from a closed state to an open state to allow the discharge of the gas.